The use of air cycle air conditioning systems as opposed to vapor cycle systems has become increasingly attractive due to growing environmentalist concern about the depletion of the earth's ozone layer resulting, inter alia, from release of fluorocarbons, which are used in vapor cycle systems.
One type of air cycle air conditioning system is described in U.S. Pat. No. 4,015,438 and employs inlet air at substantially ambient pressure which is cooled in a heat exchanger and introduced into an enclosure for cooling.